Extracorporeal Membrane Oxygenation for Unprotected Left Main Stenting in a Patient with Totally Occluded Right Coronary Artery

Coronary artery bypass graft (CABG) surgery remains the procedure of choice for the treatment of patients with unprotected severe left main (LM) disease.1–3 Percutaneous transluminal coronary angioplasty (PTCA) and stenting of LM lesions is technically feasible and an attractive alternative to patients who refuse surgery, or have continued ischemia and a prohibitively high surgical risk profile due to multiple co-morbid conditions.4–6 Recent data on LM stenting in a young, low-risk population with normal left ventricular ejection fraction and a patent right coronary artery (RCA) have shown favorable acute and long-term results.7–9 In contrast, high-risk patients undergoing unprotected LM stenting have a higher procedural complication rate and a high 30-day and 1-year mortality (9% and 11%, respectively).9 Extracorporeal Membrane Oxygenation (ECMO) has been utilized to lower complications in high-risk patients during PTCA.4,5,10 The ECMO machine provides support to the patient’s vital organs such as the brain and the kidney during episodes of hemodynamic compromise. Ott et al.4 used ECMO during angioplasty in 5 patients with unstable angina and severely reduced left ventricular ejection fraction (LVEF) (mean, 24%) with favorable procedural and short-term follow-up. Taub et al.5 applied ECMO to 7 patients with a mean LVEF of 31.5%. In their small series, one patient died from retroperitoneal hematoma unrelated to the ECMO cannulation site. Patients with severely reduced LVEF, unprotected LM and occluded RCA were not included in their series. We report the use of ECMO in a high-risk elderly female with severely reduced LVEF of 25% and a totally occluded RCA. Case Report. An 82-year-old female with no known prior cardiac history presented with chest discomfort and dyspnea. She was ruled out for myocardial infarction by serial creatinine kinase enzymes. Chest x-ray showed cardiomegaly and pulmonary edema. An echocardiogram was performed and revealed global severely reduced ejection fraction, mild mitral valve insufficiency, and mild aortic insufficiency. Persantine Cardiolite stress testing was performed and revealed significant reversible ischemia in the anterior wall with an ejection fraction of 27%. The patient was referred to our institution for cardiac angiography. Right heart catheterization revealed a mean right atrial pressure of 13 mmHg, pulmonary artery pressure of 55/30 mmHg, and a mean wedge pressure of 32 mmHg. The cardiac output was 3.7 L/minute. Left ventriculography showed a globally reduced ejection fraction of 25%. The left ventricular cavity was dilated. The left ventricular end-diastolic pressure was elevated at 35 mmHg. Coronary angiography revealed 90% ostial LM disease (Figure 1A). The left anterior descending artery was tortuous and had a 40% proximal narrowing. The left circumflex was also tortuous, with 40% proximal narrowing. A first obtuse marginal had a 70% proximal narrowing. The RCA was 100% occluded in its proximal segment and was collateralized from the left coronary system. The patient refused bypass surgery, but was willing to consider other available options. Given her poor prognosis with medical therapy alone, the feasibility of LM stenting under the protection of an ECMO was discussed. She was willing to consider this treatment approach and informed consent was obtained. In the cardiac catheterization laboratory, general anesthesia was induced after appropriate monitoring lines were established. Because of the presence of an abdominal aortic aneurysm, femoral artery cannulation and flow was felt to increase the risk of retrograde embolization. The axillary artery was, therefore, utilized for arterial cannulation. An 8 mm Hemashield graft was then sutured to the artery in an end-to-side fashion with a running suture of 5-0 Prolene. A 21 French (Fr) arterial cannula was then placed inside the graft, tied in place with umbilical tape and hooked to the appropriate lines. A venipuncture was made in the left femoral vein, the skin was incised and dilatation performed. Under fluoroscopic guidance, a 16 Fr caval drainage catheter was introduced into the right atrium and sutured in place. The arterial and venous cannulae were connected to a thrombo-resistant oxygenator. A flow rate of 1.5 L/minute was initially established. A Judkins L4 guiding catheter with side holes successfully engaged the LM. Angiographic calcification was not seen in the LM and we decided to pursue direct stenting of the ostial LM lesion with a 12 x 3.5 mm NIR stent (Boston Scientific/Scimed, Inc., Maple Grove, Minnesota). Intracoronary nitroglycerin 200 mg was then administered. Both the left circumflex and left anterior descending arteries were crossed with Sport wires. Stenting was then carried out expeditiously at 16 atmospheres (atm). The stent was post-dilated with a 15 x 4.0 mm Maverick balloon (Boston Scientific/Scimed, Inc.) at 12 atm, yielding 0% angiographic residual stenosis. Balloon inflation time did not exceed 10 seconds. Intravascular ultrasound showed excellent stent apposition to the vessel wall and a minimum luminal (MLD) diameter of 3.6 mm within the LM. Intravenous glycoprotein (GP) IIb/IIIa inhibitors were not utilized during the procedure to avoid bleeding and large hematomas, given the extent of the patient’s anticoagulation during the ECMO procedure (activated clotting time > 400 seconds) and the surgical wounds. The patient did well during the procedure with only a transient drop in her systolic blood pressure to 70 mmHg that recovered quickly after deflating the balloon. The patient was discharged home 4 days after the procedure. She was placed on clopidogrel 75 mg once daily for 1 month. She was also treated with an angiotensin-converting enzyme inhibitor (enalapril) and a beta-blocker (metoprolol) and continued on diuresis (furosemide). She was kept on aspirin indefinitely. A 6-month follow-up angiogram was recommended, but the patient refused the test. A Persantine Cardiolite test was performed at 4 months post-procedure and showed an ejection fraction of 35% with near total resolution of the ischemia previously seen in the anterior wall. At 6-month follow-up, the patient continued to do well with no reported cardiovascular events. Discussion. CABG remains the procedure of choice for treatment of severe LM disease. Medically managed significant LM disease (> 50%) carries a higher mortality rate than surgery.1–3 In the Collaborative Study in Coronary Artery Surgery (CASS) study, the median survival of patients treated surgically was 13.3 years, whereas those treated medically was 6.6 years.2 CABG for LM disease carries an in-hospital mortality of approximately 2% and a favorable low overall 3-year mortality of 15.6%.11 LM disease is generally technically amenable to catheter-based interventions. Early experience with PTCA of unprotected LM disease was disappointing because of a very high rate of sudden death on follow-up despite a relatively high procedural success rate.10,12,13 Recent experience in the treatment of unprotected LM disease in low-risk patients yielded favorable short-term and long-term results. In 3 recent trials of unprotected LM stenting in patients with normal EF, the procedural success rate was 100%, acute mortality was 0% and 1-year mortality was 2.0–2.5%.7–9 Furthermore, restenosis rate was noted to be 20–23%. This is in contrast to stenting of unprotected LM in the high-risk population, which was shown by Silvestri et al.9 to carry a 30-day mortality of 9% and a 1-year mortality of 11%. Significant risks associated with worse outcome in the treatment of unprotected LM include a severely reduced LVEF (Technical consideration. Percutaneous treatment of LM disease is technically feasible. The LM is a large vessel that is straight and amenable to stenting. In our patient, the lesion was located at the ostium. There was no angiographically visible calcification. Direct stenting was performed successfully using high pressure and short inflation times and with the stent slightly protruding into the aorta. We did not perform debulking prior to stenting. In the study published by Silvestri et al.,9 debulking was performed in only 6% of their patients. Stenting with high-pressure post-dilatation was the preferred approach to treatment with 100% procedural success. Debulking may still be an important adjunctive treatment for calcified vessels, bulky lesions and bifurcating LM disease. IVUS was utilized in our patient to assess stent apposition and final stent MLD as well as to evaluate any dissection distal to the stent. Hong et al.14 showed that IVUS, protected LM lumen cross-sectional area (CSA) > 7 mm2 carries a target lesion revascularization (TLR) rate of 7% versus 50% in patients with CSA of 400 seconds) during the ECMO procedure. Since the patient was instrumented with large-bore cannulae and had a deep incision in the axillary area, we felt that the risk of an intravenous platelet antagonist might outweigh its benefits. In 3 recent trials of elective stenting of unprotected LM lesions in low-risk patients,7–9 GP IIb/IIIa inhibitors were not utilized and a good outcome was reported. The role of these agents in elective, high-risk patients undergoing unprotected LM stenting remains unclear. Conclusion. ECMO-assisted LM stenting in patients with severely reduced LVEF and occluded RCA was performed safely in our patient. We believe that prophylactic ECMO provides effective hemodynamic support in high-risk patients undergoing unprotected LM stenting. However, the procedure requires considerable technical skill and full collaboration among the cardiologist, surgeon, catheterization laboratory nurses and technicians, anesthesiologist and perfusionist. Acknowledgment. The authors would like to thank Tina Thomas at Genesis Medical Center for her assistance in preparing this manuscript.

1. Takaro T, Hultgren HN, Lipton MJ, et al., for participants in the study group. The VA cooperative randomized study of surgery for coronary arterial occlusive disease, II: Subgroup with significant left main lesions. Circulation 1976;54(Suppl 6):III-107–III-117. 2. Caracciolo EA, Pavis KB, et al. Comparison of surgical and medical group survival in patients with left main coronary artery disease. Long-term CASS experience. Circulation 1995;91:2325–2334. 3. Varnauskas E, for the European Coronary Surgery Study Group. Twelve-year follow-up of survival in the randomized European Coronary Surgery Study. N Engl J Med 1988;319:332–337. 4. Ott RA, Mills TC, Tobis JM, et al. ECMO assisted angioplasty for cardiomyopathy patients with unstable angina. ASAIO Transactions 1990;36:M483–M485. 5. Taub JO, L’Hommedieu BD, Raithel SC, et al. Extracorporeal membrane oxygenation for percutaneous coronary angioplasty in high risk patients. ASAIO Transactions 1989;35:664–666. 6. Mani AJ, Karatepe M, Coplan NL, et al. Unprotected left main coronary artery stenting: Are we there yet? CVR&R 2001;22:585–592. 7. Park SJ, Park SW, Hong MK, et al. Stenting of unprotected left main coronary artery stenoses: Immediate and late outcomes. J Am Coll Cardiol 1998;31:37–42. 8. Wong P, Wong V, Tse KK, et al. A prospective study of elective stenting in unprotected left main coronary disease. Cathet Cardiovasc Intervent 1999;46:153–159. 9. Silvestri M, Barragan P, Sainsous J, et al. Unprotected left main coronary artery stenting: Immediate and medium-term outcomes of 140 elective procedures. J Am Coll Cardiol 2000;35:1543–1550. 10. Teirstein PS, Vogel RA, Dorros G, et al. Prophylactic versus standby cardiopulmonary support for high risk percutaneous transluminal coronary angioplasty. J Am Coll Cardiol 1993;21:590–596. 11. Ellis SG, Hill CM, Lytle BW, et al. Spectrum of surgical risk for left main coronary stenoses: Benchmark for potentially competing percutaneous therapies. Am Heart J 1998;135:335–338 12. O’Keefe J, Hartzler G, Rutherford B, et al. Left main coronary angioplasty: Early and late results of 127 acute and elective procedures. Am J Cardiol 1989;64:144–147. 13. Bentivoglio LG, VanRaden MJ, et al. Percutaneous transluminal coronary angioplasty (PTCA) in patients with relative contraindications: Results of the National Heart, Lung, and Blood Institute PTCA registry. Am J Cardiol 1984;53:82C–88C. 14. Hong M, Mintz G, Hong MK, et al. Intravascular ultrasound predictors of target lesion revascularization after stenting of protected left main coronary artery stenosis. Am J Cardiol 1999;83:175–179.